Simultaneous diffusion of cation and anion to access N, S co-coordinated Bi-sites for enhanced CO2 electroreduction
Zhiyuan Wang, Chun Wang, Yidong Hu, Shuai Yang, Jia Yang, Wenxing Chen, Huang Zhou, Fangyao Zhou, Lingxiao Wang, Junyi Du, Yafei Li, Yuen Wu
Abstract
Developing highly active single-atom sites catalysts for electrochemical reduction of CO2 is an effective and environmental-friendly strategy to promote carbon-neutral energy cycle and ameliorate global climate issues. Herein, we develop an atomically dispersed N, S co-coordinated bismuth atom sites catalyst (Bi-SAs-NS/C) via a cation and anion simultaneous diffusion strategy for electrocatalytic CO2 reduction. In this strategy, the bonded Bi cation and S anion are simultaneously diffused into the nitrogen-doped carbon layer in the form of Bi2S3. Then Bi is captured by the abundant N-rich vacancies and S is bonded with carbons support at high temperature, formed the N, S co-coordinated Bi sites. Benefiting from the simultaneous diffusion of Bi and S, different electronegative N and S can be effectively co-coordinated with Bi, forming the uniform Bi-N3S/C sites. The synthesized Bi-SAs-NS/C exhibits a high selectivity towards CO with over 88% Faradaic efficiency in a wide potential range, and achieves a maximum FECO of 98.3% at −0.8 V vs. RHE with a current density of 10.24 mA·cm−2, which can keep constant with negligible degradation in 24 h continuous electrolysis. Experimental results and theoretical calculations reveal that the significantly improved catalytic performance of Bi-SAs-NS/C than Bi-SAs-N/C is ascribed to the replacement of one coordinated-N with low electronegative S in Bi-N4C center, which can greatly reduce the energy barrier of the intermediate formation in rate-limiting step and increase the reaction kinetics. This work provides an effective strategy for rationally designing highly active single-atom sites catalysts for efficient electrocatalysis with optimized electronic structure.